Microstructural characteristics in tough pitch copper for revealing the work hardening region

Okayasu, Mitsuhiro,Taki, Tatsuya,Takasu, Satoshi,Takeuchi, Shuhei,Shiraishi, Tetsuro Techno-Press 2012 Advances in materials research Vol.1 No.4

To reveal localized plastic deformation zones in a tough pitch copper, the etching characteristics of a copper sample have been examined. The etching was carried out on a sample surface using an etchant consisting of 25 ml nitric acid solution and 75 ml water. To clarify the plastic deformation zone, the sample deformed plastically was heated to between $250^{\circ}C$ and $300^{\circ}C$ before the etching process. This is due to a change of the microstructure and crystal orientation in the plastic deformation zone producing recrystallized small grains. In this case, the plastically deformed zone is severely etched, whereas the undeformed zone is only slightly etched. Identification of the details of the deformation zone from the etching is further discussed.

Mechanical and wear properties of Cu-Al-Ni-Fe-Sn-based alloy

Okayasu, Mitsuhiro,Izuka, Daiki,Ninomiya, Yushi,Manabe, Yuki,Shiraishi, Tetsuro Techno-Press 2013 Advances in materials research Vol.2 No.4

To obtain bronze with good mechanical properties and high wear resistance, a new bronze (CADZ) is proposed on the basis of various fundamental information. The CADZ consists of the elements Al10.5, Fe4.2, Sn3.7 and Ni3.1, and its design is based on Cu-Al10.5 alloy. The Cu-10.5%Al is very hard and brittle. To obtain the high material ductility of the Cu-10.5%Al alloy, an attempt was made to add a few percent of Sn. Moreover, to make high strength of the Cu alloy, microstructure with small grains was created by the proper amount of Fe and Ni (Fe/Ni = 0.89). The mechanical properties of the CADZ sample have been examined experimentally, and those were compared with commercial bronzes. The tensile strength and wear resistance of CADZ are higher than those for commercial bronzes. Although the ductility of CADZ is the lower level, the strain to failure of CADZ is about 2.0~5.0% higher than that for the Cu-Al10.5 alloy. Details of the microstructural effects on the mechanical properties in the CADZ sample were further discussed using various experimental results.

A pilot study of pain-relieving effect of Goreisan in glossodynia with dry mouth symptoms: an open-label single-group study

Okayasu Ichiro,Mizuki Tachi,Sanuki Takuro,Kurata Shinji,Ayuse Takao 경희대학교 융합한의과학연구소 2021 Oriental Pharmacy and Experimental Medicine Vol.21 No.2

Goreisan might be a medicine to cure the pain caused by thirst and dry mouth symptom of glossodynia. All registered patients were treated with Goreisan by taking 7.5 g / day (min 3) for 2 weeks. Self-filled Visual Analogue Scale (VAS) and tongue perception test by nomo-filament. Furthermore, daily self-filled VAS evaluation was required patients’ home for two weeks during Goreisan administration. There was 57% of patients (8/14) showed “improved” after administration of 2 weeks Goreisan administration based on the criteria of 20% reduction of VAS compared to baseline. Self-filled VAS score was significant low (p = 0.006) at 2 weeks evaluation at second visit and remained lower level through 4 week observation periods compared to baseline value. QST significantly increased after 2 weeks administration of Goreisan (p = 0.008) and remained higher level through 4 week observation periods compared to baseline value. There was significant reduction of daily self-filled VAS patients’ home at day 3 and day 13 ~ day 14. (p < 0.05). There is a weak positive and negative correla-tion between Barometric pressure (hPa) and self-filled VAS scale (cm) in each patients. The administration of Goreisan for two weeks lead to significant reduction of pain perception based on the evaluation of Self-filled pain scale (VAS) and tongue perception test (QST). There is correlation between barometric pressure and self-filled VAS scale. This fact might indicate that Goreisan would be the alternative treatment for glossodynia patients. Goreisan would be a successful alternative treat-ment modality forglossodynia patients.Trial registration Current Controlled trials was registered with the UMIN Clinical TrialsRegistry (identifier: UMIN000035965, 02.21.2019).

Effects of loading conditions on the fatigue failure characteristics in a polycarbonate

Okayasu, Mitsuhiro,Yano, Kei,Shiraishi, Tetsuro Techno-Press 2014 Advances in materials research Vol.3 No.3

In this study, fatigue properties and crack growth characteristics of a polycarbonate (PC) were examined during cyclic loading at various mean stress (${\sigma}_{amp}$) and stress amplitude (${\sigma}_{mean}$) conditions. Different S vs. N and da/dN vs. ${\Delta}K$ relations were obtained depending on the loading condition. The higher fatigue strength and the higher resistance of crack growth are seen for the PC samples cyclically loaded at the higher mean stress and lower stress amplitude due to the low crack driving force. Non-linear S - N relationship was detected in the examination of the fatigue properties with changing the mean stress. This is attributed to the different crack growth rate (longer fatigue life): the sample loaded at the high mean stress with lower stress amplitude. Even if the higher stress amplitude, the low fatigue properties are obtained for the sample loaded at the higher mean stress. This was due to the accumulated strain energy to the sample, where severe plastic deformation occurs instead of crack growth (plasticity-induced crack closure). Shear bands and discontinuous crack growth band (DGB) are observed clearly on the fracture surfaces of the sample cyclically loaded at the high stress amplitude, where the lower the ${\sigma}_{mean}$, the narrower the shear band and DGB. On the other hand, final fracture occurred instantly immediately after the short crack growth occurs in the PC sample loaded at the high mean with the low ${\sigma}_{amp}$, i.e., tear fracture, in which the shear bands and DGB are not seen clearly.

Effect of 8% lidocaine spray on the sensory and pain thresholds of the skin of the face and hands evaluated by quantitative sensory testing

Okayasu, Ichiro,Komiyama, Osamu,Ayuse, Takao,De Laat, Antoon The Korean Dental Society of Anesthsiology 2018 Journal of Dental Anesthesia and Pain Medicine Vol.18 No.6

Background: Recently, we examined the effects of 2% lidocaine gel on the tactile sensory and pain thresholds of the face, tongue and hands of symptom-free individuals using quantitative sensory testing (QST); its effect was less on the skin of the face and hands than on the tongue. Consequently, instead of 2% lidocaine gel, we examined the effect of 8% lidocaine spray on the tactile sensory and pain thresholds of the skin of the face and hands of healthy volunteers. Methods: Using Semmes-Weinstein monofilaments, QST of the skin of the cheek and palm (thenar skin) was performed in 20 healthy volunteers. In each participant, two topical sprays were applied. On one side, 0.2 mL of 8% lidocaine pump spray was applied, and on the other side, 0.2 mL of saline pump spray was applied as control. In each participant, QST was performed before and 15 min after each application. Pain intensity was measured using a numeric rating scale (NRS). Results: Both the tactile detection threshold and filament-prick pain detection threshold of the cheek and thenar skin increased significantly after lidocaine application. A significant difference between the effect of lidocaine and saline applications was found on the filament-prick pain detection threshold only. NRS of the cheek skin and thenar skin decreased after application of lidocaine, and not after application of saline. Conclusion: The significant effect of applying an 8% lidocaine spray on the sensory and pain thresholds of the skin of the face and hands can be objectively scored using QST.

The development of a visual system for the detection of obstructions for visually impaired people

Mitsuhiro Okayasu 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.10

In this paper, the author presents a new visual system that can aid visually impaired people in walking. The system provides object information (that is, shape and location) through the sense of touch. This visual system depends on three different components: (i) an infrared camera sensor that detects the obstruction, (ii) a control system that measures the distance between the obstruction and the sensor, and (iii) a tooling apparatus with small pins (φ1 mm) used in forming a three-dimensional shape of the obstruction. The pins, arranged on a 6×6 matrix, move longitudinally between the retracted and extended positions based on the distance data. The pin extends individually, while the pin tip reflects the object’s outer surface. The length of the pin from the base surface is proportional to the distance of the sensor from the obstruction. An ultrasonic actuator, controlled at a 15Hz frame rate, is the driving force for the pin movement. The tactile image of the 3D shape can provide information about the obstruction.

The effects of artificial asperities on crack closing behavior in quenched and tempered medium carbon steel

Mitsuhiro Okayasu,Zhirui Wang 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.10

To better understand the effect of an asperity on crack closure behavior, K-CMOD relations were examined using artificial asperity/wedge, inserted into the fatigue crack in a three point bending specimen made of a hardened medium carbon steel. Experimental results revealed that the unloading phase of the K vs. CMOD curve exhibited a concave shape if soft artificial asperity (Al alloy) was inserted,signifying acceleration in the CMOD decrease at zero applied load. This was mainly related to elastic and plastic deformation in the wedge material during the unloading process. On the contrary, the linear unloading portion of K vs. CMOD was obtained as hard asperity (high carbon steel) was employed, which specified deceleration in the CMOD decrease at zero applied load, where the only elastic deformation in the asperity was affected. From their unloading curves, the severity of crack closure or ?Keff value was found to be related to the strength of the asperity material. The values of ?Keff were examined in two different ways, e.g., (i) the remote displacement method and (ii) the adjusted compliance ratio method (ACR). The ?Keff value, measured using both approaches, decreases with increasing wedge strength, such as hardness and yield strength. The rate of reduction in <Keff was, however, changed depending on the manner of ?Keff examination, in which the ?Keff decreased at a higher rate for the compliance ratio method and at a lower rate for the remote displacement method. The reason for this is discussed in the present work.

Effects of Sb, Sr, and Bi on the material properties of cast Al-Si-Cu alloys produced through heated mold continuous casting

Mitsuhiro Okayasu,Shuhei Takeuchi,Shaohua Wu,Toshihiro Ochi 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.3

Rare earth metals can create a fine eutectic Si structure in cast Al-Si 10.6 -Cu 2.5 (ADC12) alloys produced through heated mold continuous casting. Fine and spherical eutectic Si phases are created in the ADC12 alloys through the addition of Sr 0.04 , and fine lamellar eutectic Si phases are created through Sb and Bi addition. Crystal orientation on the face perpendicular to the casting direction is formed by [110];however, this uniform formation is collapsed in the ADC12 alloy with an increasing amount of Sr addition, such as Sr > 0.04%. The shape of the eutectic Si is statically analyzed, and the effects of the eutectic Si characteristics on the mechanical properties are examined experimentally. On the one hand, the mechanical properties of the ADC12-Sr alloy increase with increasing Sr content because of the fine eutectic Si, the randomly orientated crystal formation, and so on. On the other hand, the material ductility increases in the ADC12 alloy with increasing addition of Sb and Bi elements. A high fracture strain of approximately 14% is obtained for the ADC12-Bi1.5 alloy.

Investigation of the Proarrhythmic Effects of Antidepressants according to QT Interval, QT Dispersion and T Wave Peak-to-End Interval in the Clinical Setting

Hiroaki Okayasu,Yuji Ozeki,Kumiko Fujii,Yumiko Takano,Takahiro Shinozaki,Masami Ohrui,Kazutaka Shimoda 대한신경정신의학회 2019 PSYCHIATRY INVESTIGATION Vol.16 No.2

Objective: Some antidepressants have been implicated as risk factors for QT prolongation, which is a predictor of sudden cardiac death. However, the QT interval is considered an imperfect biomarker for proarrhythmic risk. Therefore, we reevaluated the risk of sudden cardiac death due to antidepressants using improved methods, namely, QT dispersion (QTD), T wave peak-to-end interval (Tp-e), and Tp-e/QT ratio. Methods: We compared the effects of antidepressants on QTc (QT/RR1/3), QTD, Tp-e, and Tp-e/QT ratio in 378 patients with mood disorder. We also compared each index between 165 healthy controls and 215 randomly selected age-matched patients. Results: Age (p<0.01), sex (p<0.05), tricyclic antidepressant (TCA) use (p<0.05), and clomipramine (p<0.01) and mianserin (p<0.05) use in particular, significantly associated with a prolonged QTc. We also found that age (p<0.01), TCA use (p<0.05), and clomipramine (p<0.01) and mianserin (p<0.05) use in particular, significantly prolonged QTD. However, there was no correlation between each variable and Tp-e or Tp-e/QT ratio. Significant differences in QTc and QTD were found between the patients and healthy controls. Conclusion: From our results, prediction of risk of sudden cardiac death by QTD, Tp-e, or Tp-e/QT ratio was inconsistent. Increased QTD may be more suitable for predicting sudden cardiac death due to antidepressants.

EMISSION OF NITROUS OXIDE FROM HIGH RATE NITRIFICATION AND DENITRIFICATION BY MIXED LIQUOR CIRCULATING PROCESS AND SEQUENCING BATCH REACTOR PROCESS

( Yuji Okayasu,Isaya Abe,Yoshitaka Matsuo ) 한국물환경학회 1997 제6차 국제수질보전학회 아시아 태평양지역 학술회의 Vol.1 No.-